The proposed study will take place on the outpatient adolescent unit at the Center on Alcoholism, Substance Abuse and other Addictions (CASAA) of UNM. The general objective is to test the effectiveness of the engagement and treatment components of the Structural Strategic Systems (SSS) family intervention with New Mexican Hispanic youths, 13-18 years old and families. This is a replication of treatment studies of Cuban American youths by Szapocznik et al. in Miami. It explores the issue of treatment effectiveness relative to observed differences in family functioning among Hispanic cultures in the US, comparing Cuban American with Hispanic/Mexican American. It also looks at similar responses to treatment despite cultural differences. The SSS intervention will be compared with two control/comparison conditions, SSS therapy without engagement and group therapy. Two main research questions are examined: How effective is the SSS intervention (engagement plus family therapy) in engaging and retaining young Hispanic polydrug abusers and their families in treatment compared with the control conditions? And, how effective is the SSS intervention in treating clients relative to control condition? Relationships between family functioning, drug use and psychosocial adjustment of youths will be explored. A prospective design will be employed with random assignment to the three treatment conditions, each carried out over a modal 16 sessions. Treatments will follow the guidelines of manuals developed in Miami and therapists will be rated regarding adherence to treatment guidelines. Each treatment condition will be conducted by two therapists each Hispanic and Anglo, the ethnic mix of clinical staff. This will allow assessment of the effect of individual therapist/client helping alliances. Outcome measures will be administered at pretreatment, completion of treatment, and 6 and 12 month follow-up. Measures of outcome assess the effectiveness of the interventions along five dimensions: 1) rate of engagement in therapy; 2) rate of retention in therapy; 3) reduction or cessation of drug abuse; 4) improvement in psychosocial adjustment of the client; and 5) improvement in family functioning. Possible confounds are the quality of the therapist-client alliance; current family history of substance abuse or psychiatric illness; significant group differences in therapy contact hours, and in pre-test (intake) scores.